The present invention relates to the protection of foodstuffs and cosmetic products against the effects of oxygen.
Anti-oxidants for use in foodstuffs or cosmetics should have good anti-oxidant activity, be stable, colourless, organoleptically neutral and should be guaranteed to be harmless.
Known anti-oxidants, which are widely used, are obtained synthetically and are generally phenolic materials, for example butylhydroxyanisole (B.H.A.) and butylhydroxytoluene (B.H.T.), individually or in synergistic mixtures. Other phenolic derivatives are known to have anti-oxidant properties, for example pyrogallol which suffers from the disadvantages of being relatively toxic, or gallates, more particularly propyl, octyl, or lauryl gallates. Although these materials unmistakeably have anti-oxidant activity, good stability, are colourless and are acknowledged as being harmless and neutral with respect to food, their use is in the process of being vigorously challenged by a number of food laws.
Attempts have been made to utilise the fact that certain natural products contain anti-oxidants. A good many fatty substances, for example, are protected naturally against oxidation by the tocopherols which they contain, but their activity is poor. Proposals have also been made to extract the anti-oxidants contained in plant matter, such as spices and more particularly in Labiatae, such as sage or rosemary. The proposed methods make use of a chemical agent and are therefore questionable for the same reason as synthetic antioxdants or necessitate the extraction by solvents of crushed plant matter, generally followed by elaborate treatments for distilling, decolourisation and deodorization of the extracts. Even if the anti-oxidant activity of these extracts is acknowledged their use is limited because in almost every case there remains some lingering colour, smell and taste of the spice which was used.
A proposal has been made in Japanese patent No. 71.039.058 to protect sea foods from oxidation by adding catechols, gallocatechols and 3-galloyl derivatives of these compounds which are condensed natural tannins and consist principally of esters of gallic acid and flavan-3-ols which are found in tea leaves. According to this patent the anti-oxidant compounds are extracted, i.e., by ethanol. The colour is removed from the extract by active carbon and the solvent is evaporated.